Expansion-reamer.



G. 0. SCHELLENBAGH.

EXPANSION REAMBR.

APPLICATION FILED DBO. 20, 1912.

1,'?4,. Patented. Oct. 7, 1913.

2 SHEETS-SHEET l.

G. O. SGHELLENBAGH. EXPANSION RBAMER. APPLICATION nun DEC. 20, 1912.

135.97%,820; Patented 0013.7,1913.

2 sun's-sum 2.

COLUMBIA PLANOGRAPH co.,WAS|-nNuTON, D. c

CHARLES Op SGHELLENBACI-Ip OF- CINGINNATI,-- OBI-IO Munster-remnant nosagssoa Specification of letters Patent.

riaeemeaobm, 191s taini I1'6W' 1'I1'd useful li'i'i-proveniei'itsf in pansion Reamersy of whiclrtlie following; 1s a specification.-

My invention relates to an expansib'le reamer; of"wh'at may be "termed the PGIIHEH nent or standard t pe, having provision for predetermined periodic" expansion; periodic regrinding andreex'pansion: I

One of the objects ofthe inventionis to produce a compactgunitary; rigid reamer;

with the blades constituting approximately fixed components of tl1e'body; butfstill' sus ceptible of a COnsidera'bl-e but circumferen tially uniformprecision expansion relative to the body.

Another 'obj ect of the in-ve'ntion is to produce expansion means exerting pressuresufli cient to overcome th-efriction-fit of the blades seated Within-the body and-"preferably exertingits maximumdorce approximately at one end ofthe-reamer;

It is to be understood"th'atthe expansion provision is designed" to compensate" for" Wear of E the blades and regrinding.

In practice the blades are 1 set into thebody the'diameter of the-cutting=circle being slightly in-exeessofthe diameter of the desired cutting circle;thecu'tting}blades' being ground doWnto the-"requisite prede' termined degree. As theblades Wear; they are expanded and reground to the'diameter of the predetermined cutting circle. The requisite expansionfor one of "these periodic operations may be as slight as threeonethousand-ths of an inch, or less, but the full expansion capacity in a small reamer may amount to three thirty-seconds of an -inch,

or even one eighth" of an inch in a largerreamer. Therefore, the-device isof extreme durability, having substantially the advan= tages-of anintegral cutting: tool -combined with a Wide range of expansive capacity compensating for the blade Wear inherent in the usage of a tool of this character.

. Of course, the invention is susceptible of various embodiments, for instance, it is im-.

material Whether thezblade-be seated in a... body of solid shank-f0r1n With a centrally; bored end or Whether the body is hollow-to constitute a shell reamer.

4 is-a central longitudinalseetion; Fig. 5- is 1 central longitudinal section: through asoeket forni of reamer; sho'wing=- a slight modification-of blade and expander.

In"Fig-.'1, 1 represents-thebody formed with the central bore 2-, provided- -vvi-thvery; fine-screw threads 3, atits' innerend; Pr'ef erably the diameter ofth'e bore is enlarged at its forward end; as indicated by4, -Fig. 4'. This is the SlitIlk fOT-hiflf re'am'erf, The' shanlr exterior-1y I is also' formed 5 with a series of longitudinal radial grooves 5; terminating at" their outer ends-in slots 6, penetrating the Walls of theouter end of the' shank. This is-slrown' in dotted lin'es,-Fig; and" is also clearly disclosed-by the comparative views, Figs; Qand The-cutting'endof the body has the conventional exterior 0on figuration; the plane faces- 7 serially throWr-'- ing the cutting edgesof the "blades :inte re lief, while' theshudders 8 form: abutments' for the rear faces of the blades, as shown: in Fig." 3. i

9 represents" the blades, the' rear ends 10 of Which are respectively positioned in the grooves 5-," Whilethe 5 forward 3 ends having theinwardextensions 11 positioned in the slots 6; theinner edges of-theextensions-ll are formed "with slightly inwardly-tapering surfaces 12W-ithi-n thebody; The extensions 11 provide blade shoulders 5O, -WhlCl1 abut the-body portions 51, defined by the inner terminals of'slots 6, serving: to longitudinal-l y position the blades on the body.

13 represents the expander having the fine screw threads'lliat' its inner end, en-i gaging threads?) of the body; i

15 representsthescrew head oftheexpander formed with theslightly inwardly tapering peripheral surface 16; thetapers! 16 and 12 beingapproximately of'the same degree.

The lateral dimensions ofthe blades-rela= tive to the grooves and slots are approximatelythe same constitutingwhat is known as aclose, or friction-fit, requiring a considerable circumferential pressure to seat the blades in the grooves and slots of the body.

When so fitted,'the blades constitute approximately fixed components of the body. This necessitates the provision of" anexpander with capacity for exerting an outward or radial compression exerting its force at the forward ends of the blades, superior in degree to the fitting compression for seating the blades, and this superior compression is realized by the character" of the fine pitch threads 3 and 14, cotiperative with the wedging effect inherent from the engagement of the very slight taper surfaces 12, 16, respectively,-of the blades and expander head.

It is to be understood that the requisite degree of blade expansion for this type of reamer for a given blade setting, is relatively very slight, in practice a given adjustment may not necessitate, say over three one-thousandths of an inch of expansion, but such expansion must be circumferentially uniform and of precision characteristic, whereas the full range of permissive expansion is quite considerable. As will be seen,- in the preferred form, the individual blades are not bodily expanded equally but the maximum force is exerted at the forward or cutting edges of the blades in the coincident plane of the taper surfaces 12, 16. The turning of the expander exerts only a slightly preponderant compression relative to the friction-fit of the blades in the body so that while the blades are thus outwardly expressed, they still constitute approximately fixed components of the body, being still retained under the initial compression of friction-fit obtaining. The cutting edges of'theblades may be reground without displacement and reexpanded, as occasion requires.

In Fig. 5, I have shown a shell form of reamer, that is to say, the central bore extends entirely through the body. In this modification the slots 6 are formed at both ends of the grooves 5. The blade may have inward extensions 40, 41, at its opposite shown the expander of hollow form, thus constituting a reamer of the shell type,

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents adapted to be secured upon the intermediate portion of an arbor.

I do not wish to be limited to the details the invention, except as the specific phases of the invention are clearly indicated in the claims.

Having described my invention, I claim l. A reamer comprising a bored body formed with an external longitudinal series of radial grooves forwardly terminating in slots penetrating the walls at the end of the body, the inner end of said body bore being formed with fine screw threads, blades having inward extensions at their forward ends, said blades being forcibly compressed into said grooves with a friction fit, the blade extensions extending entirely through the body slots, an expander formed with threads at its inner ends engaging the body threads and formed with a head having a'slightly, inwardly tapering peripheral surface engaging the inner edges of the blade extensions within the body, the cohperative effect of the fine threads and taper pitch of the expander head, producing, when the expander is turned, an expanding pressure slightly in excess of the frictional hold ofv the blades into the formed with external slots and grooves ex 7 tending longitudinally of the body, a series of radial blades friction-fitted into the grooves with inward extensions penetrating entirely through the slots so as to definitely position the blades longitudinally in said grooves and slots, an expander having screw threaded relations with the body, saidexpander and blades being formed with taper contact surfaces within the body, adapted to overcome the frictional hold and radially v expand the blades in theirseats.

In testimony whereof, my hand.

CHARLES o. scr ELLENBAcH. v l/Vitnesses I OLIVER B. Karena, CLAREN on B. Fosrnn.

' Washington, D. C.

Ihave hereunto set. 

